Aem air fuel ratio gauge flashes 3 times

So you need higher octane to make sure it doesn't catch on fire on its own before you want it to by firing the sparkplug. This can be from a glowing hot spark plug or just too much heat in the air when it is being compressed. Sometimes the fuel mixture can catch on fire in the cylinder way too early and then you have a huge explosion while the piston is still coming up, fighting it, and can cause catastrophic engine damage. High performance engines at times need high octane fuel to keep it from catching on fire before the sparkplug catches it on fire on purpose. E85 having an octane rating somewhere around 100-110 octane, so it is harder to catch on fire. It's easier to catch low octane fuel on fire basically. You can tune a carb for ethanol though, but then it will be pig rich on gasoline.Р В РІР‚СњР вЂ™Р’В«ack to octane, octane is the measure of resistance to ignition. If you run ethanol in a carb tuned for gasoline then you will be mixing the same amount of fuel when you should be adding more and you will be lean.

So you need more ethanol for the same amount of air to get a proper fire than you do with gasoline.Р В РІР‚СњР В РІР‚РЋlex fuel engines have a computer that sees the ethanol content of the fuel, via a flex fuel sensor, and sees the AFR of the burnt exhaust, via O2 sensors, so the computer can add more fuel at the same amount of airflow to get back to stoichiometric with changing fuels.Р В РІР‚СњР вЂ™Р’В¬arburetors don't do that, they are tuned for a specific fuel type. So all else equal you will get worse MPG on ethanol than gas because of the energy content difference.Р В РІР‚СњР вЂ™Р’В®thanol requires a different Air Fuel Ratio for a proper burn compared to gasoline.Р В РІР‚СњР В РІР‚С›s you can see gasoline has a stoichiometric ratio of 14.7 parts air to 1 part gasoline while ethanol's stoichiometric ratio is 9.8 parts air to 1 part E85. A flex-fuel vehicle will experience about 76% of the fuel mileage MPG when using E85 (85% ethanol ) products as compared to 100% gasoline. 1.5 gallons of ethanol has the same energy content as 1.0 gallon of gasoline. 116,090 = BTU of energy in a gallon of gasoline 76,000 = BTU of energy in a gallon of ethanol B. You have to fire the sparkplug earlier to get it burning right before the piston gets to the top vs straight gasoline.Р В РІР‚СњР В РІР‚С›. This is needed for high compression engines and forced induction engines.Р В РІР‚СњР вЂ™Р’В®thanol burns even slower, has a much lower energy density, and is much more resistant to ignition.Р В РІР‚СњР вЂ™Р’В®thanol burns so much slower that flex fuel applications run a lot more ignition advance with high ethanol content to get peak cylinder pressure back near TDC. Higher octane gas is harder to ignite and burns slower. The additives serve to slow down the burn of the fuel and increase it's resistance to ignition.

In gasoline the octane is artificially increased with additives. You should get better gas mileage and more power with the lower octane gas.

Aem air fuel ratio gauge flashes 3 times